tramming query

[Steve HuckinsParticipant @stevehuckins53362]

Morning all.

I have my new Amadeal VM25L Mill now.  I have made a solid arm to hold an indicator so that I can tram the table following various advice.  It has worked ok but I get a slightly different result when tramming with the quill lock off as to when it is on.  Should I use the all axis locked and quill locked when tramming ?  My gut feeling is to tram with everything locked ?

Steve

[John HaineParticipant @johnhaine32865]

I agree.

[Mike HurleyParticipant @mikehurley60381]

The quill lock in these machines is normally fairly simple and will naturally apply force on one side of the quill, this will move it a minute amount to the opposite side (due to manufacturing tolerences).

Yes – lock it, as more often than not that is how it will be in use for milling.

Mike

[Brian WoodParticipant @brianwood45127]

Hello Steve,

I agree with the advice above but would like to add that there is a quick way to tram vertical mills that you may care to try.

If you have a faceplate or even a simple flat disc you have trued on a lathe that will fit onto spindle fitting hardware, then by winding the work-head down so that you can use the machine quill to hold the face of the plate down in contact with the table surface; you can tram in both directions by shining a light at the contact surface and correct the lean accordingly. Lock the adjustments once you are happy with the outcome.

It is a lot quicker to do and I would say sufficiently accurate for most work

Regards   Brian

[SillyOldDufferModerator @sillyoldduffer]

Yes, lock them.  It’s because the table and quill movements are adjustable.   Getting them spot on is somewhat fiddly, and as over-tightening causes rapid wear, it’s usual for them to be deliberately left a little slack.   As applying the locks always causes slight movement, it pays to measure tram with them locked.  This is closer to what happens when cutting – all the locks that can be applied should be to stop unwanted movements.

By the by, I advise beginners not to start by measuring and adjusting a new machine.    The problem is that taking accurate measurements,  understanding what they mean, and knowing what to do about them are all skilled work.  Unfortunately, it’s all too easy to get completely wrapped round the axle due to minor errors of technique and misunderstandings.  Even experienced machinists are led astray.

A better approach, I think, is to start by using the machine to cut metal.   Machining is an acquired skill, used to be a 7 year apprenticeship, so don’t worry too much if results are poor at first.   The main point though is it’s much easier to measure the job than it is to measure the machine, and there’s no need to mess with a machine that produces good work.

However, if jobs are persistently mis-sized, and tooling, material, work-holding and operator errors have all been eliminated, then it might be time to measure the machine.   May not be necessary because cutting metal is a good test for other reasons; the whole machine is exercised, perhaps emitting obvious clues like visible movement, horrible noises or magic smoke!

The VM25 looks similar to my trusty Warco.  Though I’m very happy with mine, bear in mind these are hobby machines, not high-speed industrial metal-munchers or super accurate jig-borers!

Dave

[Martin ConnellyParticipant @martinconnelly55370]

Usually the Grizzly manuals for these Chinese machines is more informative than is typical in the UK so I had a look to see what it says regarding tramming, the answer is nothing. There may be other useful information though so here is a link to it, but note that there may be slight differences with your machine.

It does show that the spindle lock is simply the end of a small brass rod pressing on one side of the spindle assembly to lock it. That seems to me to be a little less stable than I would have liked for a spindle lock.

Martin C

https://cdn0.grizzly.com/manuals/g0759_m.pdf

[PeteParticipant @pete41194]

In theory that quill lock should be only pressing or clamping the spindle up tight against the opposite bore wall and taking up what should only be a few .001″ of the clearance in the head. If your seeing changes between a locked or unlocked spindle, it seems likely the column isn’t yet square to the table and/or the head is also not square to the table. Or there’s something not quite correct within the head that’s allowing that spindle to deflect away from the lock as it’s applied. Both of those Z axis misalignment’s are common on these mills and are usually a time consuming job to get correct. It’s also a lengthy procedure to fully explain here. About the best way I know to explain it would be with this video. https://www.youtube.com/watch?v=kF3LfP3W-Ec&t=42s

But in my opinion, his order of checks are a bit faulty. I would first spotlessly clean the table ways, inspect for straightness, de-burr and smooth the Z axis head gib, the same for both the X,Y gibs. Then properly adjust each one. You want each axis to move smoothly over there full travel but not too tight or with any real slack between the parts. At that point you would only shim or adjust the column in both X,Y axis until it is verified as being square to the table. That’s your known reference point you start from. Then you start checking the spindles Z axis travel. Once that’s correct you can then double check the tram between the spindle and table. Machine tool alignments need to be visualized in three dimension’s. And any single machine tool slide has up to 6 axes of possible inaccuracy or combinations in various amounts of any or even up to all 6. Up, down, twist or roll in either direction, as well as left,right. They can or could also switch directions along a slide.

 

Fortunately most of these checks only need to be done once and then much later after lots of use and the unavoidable wear happens after you have initially verified everything is as correct as you can get it. After that the usual tramming of the head to the table will suffice. I’d also warn you that you will see some variation in the squareness or alignment of the column between where exactly the head is positioned on that column. Down lower the column is of course much stiffer, with the head up high on the column then you’ll start seeing the column deflect a bit from just the weight of the head. In simple engineering terms that’s known as beam deflection. There’s also a common misunderstanding about these checks. There in reality a static no load test check. Under any dynamic cutting loads as your using it, the machine will also have varying amounts of deflection throughout the whole machine depending on the material hardness your cutting, tool condition, depth of cut, feed rate and which axis your using.

 

[Steve HuckinsParticipant @stevehuckins53362]

Thanks to all for your contributions. I am happy now that I have trammed the table to the best of my abilities.

I agree that just making a start on cutting metal is good advice and I have begun some tee nuts.

However, I have waiting in the box, a Stuart models S50 from casting which I am excited to get going on. Although I suspect many of you have completed this model, for a beginner like me I think its a good first project.

The information on the Grizzly site is great and it is obvious that many Mills and Lathes are from the same manufacturer and just re badged.

On another matter, can I ask what chart you would use for SFM of various metals.  I see quite few when I search online and all seem a little different.  I would prefer a simple chart for the most common materials we use.  M/Steel, C/Iron, Drill rod /silver steel, Aluminium, Brass, Bronze for example.  I can then calculate the RPM values as per the formula.  As mentioned, I am a fairly raw beginner.

Cheers

Steve

[JasonBModerator @jasonb]

one thing to bear in mind when working out your cutting speed is that the hobby mills with their electronic variable speed work better when running in at least the top half of their rev range if not the top 1/4 so don’t go too big on the cutters unless there is a specific need to do so as they will run faster (revs)for the same given surface cutting speed. The S50 could be done with nothing larger than a 6mm cutter.

Type of cutter will also affect the cutting speed for the material, uncoated HSS being the slowest, then coated HSS, uncoated carbide and finally coated carbide.

I probably run a bit higher than others but for the usual 3-flute coated HSS around these figures seem to work for me

Steel 30m/min

Cast Iron 25m/min

I prefer the non ferrous specific cutters for those metals which are uncoated, HSS would be

Aluminium 100m/min

Brass/Bronze/GM 80m/min.

2.5 to 3 times that if using Carbide

[Steve HuckinsParticipant @stevehuckins53362]

Thanks Jason.  This is valuable advice and I will take it on board.

[old martParticipant @oldmart]

I almost always lock the quill on mills when cutting metal, even adding a little lock when drilling and boring. So tramming will be more accurate with the lock applied. One thing that I have never tried is to check if the tram is consistant with the quill at both ends of its travel.

[Howard LewisParticipant @howardlewis46836]

FWIW,

Use the machines, on non vital material. Better to make the mistakes, and learn, on the odd bit of mild steel than on expensive castings.

Learn by making a few simple tools, learning how to produce a good finish, while making a tap Wrench, or a Tailstock sliding die holder. If the finish is a bit rough, or some non vital dimension is out, it won’t matter as much as if you messed up the cylinder bore!

When experience, and confidence has been gained, then tackle a kit.

Howard

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